Isotopes of fluorine (9F)
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
18F trace 109.734 min β+ 18O
19F 100% stable
Standard atomic weight Ar°(F)
  • 18.998403162±0.000000005
  • 18.998±0.001 (abridged)[2][3]

Fluorine (9F) has 18 known isotopes ranging from 13
F
 to 31
F
 (with the exception of 30
F
) and two isomers (18m
F
 and 26m
F
). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element.

The longest-lived radioisotope is 18
F
; it has a half-life of 109.734(8) min. All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is 14
F
, whose half-life is 500(60) yoctoseconds,[4] corresponding to a resonance width of 910(100) keV.

List of isotopes

Nuclide
[n 1]		 Z N Isotopic mass (Da)[5]
[n 2][n 3]		 Half-life[4]
[n 4]		 Decay
mode[4]
[n 5]		 Daughter
isotope
[n 6]		 Spin and
parity[4]
[n 7][n 4]		 Natural abundance (mole fraction)
Excitation energy Normal proportion[4] Range of variation
13
F
[6]		 9 4 13.045120(540)# p ?[n 8] 12
O
 ?		 1/2+#
14
F
 9 5 14.034320(40) 500(60) ys
[910(100) keV]		 p ?[n 8] 13
O
 ?		 2−
15
F
 9 6 15.017785(15) 1.1(3) zs
[376 keV]		 p 14
O
 1/2+
16
F
 9 7 16.011460(6) 21(5) zs
[21.3(5.1) keV]		 p 15
O
 0−
17
F
[n 9]		 9 8 17.00209524(27) 64.370(27) s β+ 17
O
 5/2+
18
F
[n 10]		 9 9 18.0009373(5) 109.734(8) min β+ 18
O
 1+ Trace
18m
F
 1121.36(15) keV 162(7) ns IT 18
F
 5+
19
F
 9 10 18.998403162067(883) Stable 1/2+ 1
20
F
 9 11 19.99998125(3) 11.0062(80) s β− 20
Ne
 2+
21
F
 9 12 20.9999489(19) 4.158(20) s β− 21
Ne
 5/2+
22
F
 9 13 22.002999(13) 4.23(4) s β− (> 89%) 22
Ne
 (4+)
β−n (< 11%) 21
Ne
23
F
 9 14 23.003530(40) 2.23(14) s β− (> 86%) 23
Ne
 5/2+
β−n (< 14%) 22
Ne
24
F
 9 15 24.008100(100) 384(16) ms β− (> 94.1%) 24
Ne
 3+
β−n (< 5.9%) 23
Ne
25
F
 9 16 25.012170(100) 80(9) ms β− (76.9(4.5)%) 25
Ne
 (5/2+)
β−n (23.1(4.5)%) 24
Ne
β−2n ?[n 8] 23
Ne
 ?
26
F
 9 17 26.020050(110) 8.2(9) ms β− (86.5(4.0)%) 26
Ne
 1+
β−n (13.5(4.0)%) 25
Ne
β−2n ?[n 8] 24
Ne
 ?
26m
F
 643.4(1) keV 2.2(1) ms IT (82(11)%) 26
F
 (4+)
β−n (12(8)%) 25
Ne
β− ?[n 8] 26
Ne
 ?
27
F
 9 18 27.026980(130) 5.0(2) ms β−n (77(21)%) 26
Ne
 5/2+#
β− (23(21)%) 27
Ne
β−2n ?[n 8] 25
Ne
 ?
28
F
 9 19 28.035860(130) 46 zs n 27
F
 (4−)
29
F
 9 20 29.043100(560) 2.5(3) ms β−n (60(40)%) 28
Ne
 (5/2+)
β− (40(40)%) 29
Ne
β−2n ?[n 8] 27
Ne
 ?
31
F
 9 22 31.06020(570)# 2 ms# [> 260 ns] β− ?[n 8] 31
Ne
 ?		 5/2+#
β−n ?[n 8] 30
Ne
 ?
β−2n ?[n 8] 29
Ne
 ?
This table header & footer:
  1. ↑ mF – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ↑ Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
    n:Neutron emission
    p:Proton emission
  6. ↑ Bold symbol as daughter – Daughter product is stable.
  7. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  8. 1 2 3 4 5 6 7 8 9 10 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
  9. ↑ Intermediate product of various CNO cycles in stellar nucleosynthesis as part of the process producing helium from hydrogen
  10. ↑ Has medicinal uses

Fluorine-18

Of the unstable nuclides of fluorine, 18
F
 has the longest half-life, 109.734(8) min. It decays to 18
O
 via β+ decay. For this reason 18
F
 is a commercially important source of positrons. Its major value is in the production of the radiopharmaceutical fludeoxyglucose, used in positron emission tomography in medicine.

Fluorine-18 is the lightest unstable nuclide with equal odd numbers of protons and neutrons, having 9 of each. (See also the "magic numbers" discussion of nuclide stability.)[7]

Fluorine-19

Fluorine-19 is the only stable isotope of fluorine. Its abundance is 100%; no other isotopes of fluorine exist in significant quantities. Its binding energy is 147801.3648(38) keV. Fluorine-19 is NMR-active with a spin of 1/2+, so it is used in fluorine-19 NMR spectroscopy.

Fluorine-20

Fluorine-20 is an unstable isotope of fluorine. It has a half-life of 11.0062(80) s and decays via beta decay to the stable nuclide 20
Ne
. Its specific radioactivity is 1.8693(14)×10+21 Bq/g and has a mean lifetime of 15.879(12) s.

Fluorine-21

Fluorine-21, as with fluorine-20, is also an unstable isotope of fluorine. It has a half-life of 4.158(20) s. It undergoes beta decay as well, decaying to 21
Ne
, which is a stable nuclide. Its specific activity is 4.781(23)×10+21 Bq/g.

Isomers

Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized.[4] The half-life of 18m
F
 before it undergoes isomeric transition is 162(7) nanoseconds.[4] This is less than the decay half-life of any of the fluorine radioisotope nuclear ground states except for mass numbers 14–16, 28, and 31. [8] The half-life of 26m
F
 is 2.2(1) milliseconds; it decays mainly to its ground state of 26
F
 or (rarely, via beta-minus decay) to one of high excited states of 26
Ne
 with delayed neutron emission.[4]

References

  1. ↑ Chisté & Bé 2011.
  2. ↑ "Standard Atomic Weights: Fluorine". CIAAW. 2021.
  3. ↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. 1 2 3 4 5 6 7 8 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  5. ↑ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  6. ↑ Charity, R. J. (2 April 2021). "Observation of the Exotic Isotope 13 F Located Four Neutrons beyond the Proton Drip Line". Physical Review Letters. 126 (13): 2501. Bibcode:2021PhRvL.126m2501C. doi:10.1103/PhysRevLett.126.132501. OSTI 1773500. PMID 33861136. S2CID 233259561. Retrieved 5 April 2021.
  7. ↑ National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  8. ↑ Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.

Sources

  • Chisté, V.; Bé, M. M. (2011). "F-18" (PDF). In Bé, M. M.; Coursol, N.; Duchemin, B.; Lagoutine, F.; et al. (eds.). Table de radionucléides (Report). CEA (Commissariat à l'énergie atomique et aux énergies alternatives), LIST, LNE-LNHB (Laboratoire National Henri Becquerel/Commissariat à l'Energie Atomique). Archived from the original (PDF) on 11 August 2020. Retrieved 15 June 2011.
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